1. Field of the Invention
The present invention relates to an image forming apparatus capable of printing a disc and a disc-printing unit for such an image forming apparatus, and more particularly, to an image forming apparatus having a printing function for printing a title, a design, or the like on a surface of the disc and a disc-printing unit that is applied to such an image forming apparatus.
2. Description of the Related Art
Recently, various types of storage media have appeared in the market, among which discs are largely used in general because they are inexpensive and conveniently portable. Descriptions, such as words, letters, characters, symbols, communications, etc., directly describing a title, an outline, or the like, are often written or formed on the surfaces of discs, so that the contents stored in the discs can be easily determined or known. However, these descriptions, usually made by hand using a pen or the like, are problem-some in that the descriptions may easily be erased, and in particular, the quality of external appearance of the discs may be compromised by the description.
Recently there has been proposed a disc-printing unit as shown in FIG. 1 (see Japanese Patent Publication No. JP 9-265760), which can print contents or patterns designed by consumers on surfaces of discs. As can be seen from FIG. 1, the conventional disc-printing unit 100 comprises a turntable 110, on which a disc 1 is seated, a rotary motor 115 for rotating the turntable 110, and a printing head 120 located above the turntable 110. The printing head 120 is moved and guided in the radial direction of the turntable 110 by a guide rod 121 that is driven by a moving motor 125. The disc-printing unit 100 further comprises an optical head 130 for illuminating a laser beam to the disc 1 in order to reproduce information stored in the disc 1, an optical head driving motor 135, and an optical head guide rod 131.
With this conventional construction, if a signal corresponding to a print image is applied from the outside, a control section converts the print image into a dot image of a polar coordinate format about a rotational axis of the turntable 110. Then, the moving motor 125 is controlled by the control section on the basis of the converted dot image, such that the printing head prints the contents or designs on the surface of the disc 1 while being moved in the radial direction of the disc 1. Concurrently, the applied print image can be printed while the driving of the rotary motor 115 and the ink-jet through the print head 120 are intermitted relative to each other.
However, the conventional disc-printing unit 100 is complicated to construct. In particular, the optical head 130 for reading and writing information of a disc 1 and its driving means 131, 135, and a printing head 120 for performing printing on the disc 1 and its driving means 121, 125 need to be installed together within a given space. In addition, a position-detecting sensor must be provided for detecting the position of the printing head 120 on the polar coordinate within a moving area of the printing head 120, and a rotary motor 115 must also be provided. Furthermore, the moving motor 125, the rotary motor 115, and the driving motor 135 must be separately provided. Due to such a complicated construction, the manufacturing costs increase.
Although the conventional disc-printing unit 100 can both read and write information, it would be desirable if the conventional disc-printing unit could be applied to an inexpensive printer, one that prints on a print paper, while simplifying the construction thereof. It is possible to provide an inexpensive printer with a function for printing a disc being added beyond an original printer function, i.e. a function for printing a print paper.